/*
 * Copyright 2013 Eediom Inc.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.araqne.log.api;

import java.io.EOFException;
import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.util.HashMap;
import java.util.Map;

public class WtmpLogger extends AbstractLogger implements Reconfigurable {
	private final org.slf4j.Logger slog = org.slf4j.LoggerFactory.getLogger(WtmpLogger.class);
	private final File dataDir;
	private String path;

	public WtmpLogger(LoggerSpecification spec, LoggerFactory factory) {
		super(spec, factory);
		dataDir = new File(System.getProperty("araqne.data.dir"), "araqne-log-api");
		dataDir.mkdirs();

		path = spec.getConfig().get("path");

		// try migration at boot
		File oldLastFile = getLastLogFile();
		if (oldLastFile.exists()) {
			Map<String, LastPosition> lastPositions = LastPositionHelper.readLastPositions(oldLastFile);
			setStates(LastPositionHelper.serialize(lastPositions));
			oldLastFile.renameTo(new File(oldLastFile.getAbsolutePath() + ".migrated"));
		}
	}

	@Override
	public void onConfigChange(Map<String, String> oldConfigs, Map<String, String> newConfigs) {
		if (!oldConfigs.get("path").equals(newConfigs.get("path"))) {
			this.path = newConfigs.get("path");
			setStates(new HashMap<String, Object>());
		}
	}

	private WtmpEntryParser buildParser(String server) {
		if (server == null)
			return new WtmpEntryParserLinux();

		server = server.toLowerCase();

		if (server.equals("solaris"))
			return new WtmpEntryParserSolaris();
		else if (server.equals("aix"))
			return new WtmpEntryParserAix();
		else if (server.equals("hpux"))
			return new WtmpEntryParserHpUx();

		return new WtmpEntryParserLinux();
	}

	@Override
	protected void runOnce() {
		Map<String, LastPosition> lastPositions = LastPositionHelper.deserialize(getStates());
		LastPosition inform = lastPositions.get(path);
		if (inform == null)
			inform = new LastPosition(path);
		long pos = inform.getPosition();

		File wtmpFile = new File(path);
		if (!wtmpFile.exists()) {
			slog.debug("araqne log api: logger [{}] wtmp file [{}] doesn't exist", getFullName(), path);
			return;
		}

		if (!wtmpFile.canRead()) {
			slog.debug("araqne log api: logger [{}] wtmp file [{}] no read permission", getFullName(), path);
			return;
		}

		// log rotated case, reset read offset
		if (wtmpFile.length() < pos) {
			pos = 0;
		}

		WtmpEntryParser parser = buildParser(getConfigs().get("server"));
		int blockSize = parser.getBlockSize();

		RandomAccessFile raf = null;
		try {

			raf = new RandomAccessFile(wtmpFile, "r");
			raf.seek(pos);
			byte[] block = new byte[blockSize];

			while (true) {
				raf.readFully(block);

				WtmpEntry e = parser.parseEntry(ByteBuffer.wrap(block));

				Map<String, Object> data = new HashMap<String, Object>();
				data.put("type", e.getType().toString());
				data.put("host", e.getHost());
				data.put("pid", e.getPid());
				data.put("session", e.getSession());
				data.put("user", e.getUser());

				data.put("device", e.getDeviceName());
				data.put("inittab_id", e.getInitTabId());

				write(new SimpleLog(e.getDate(), getFullName(), data));
				pos += blockSize;
			}
		} catch (EOFException e) {
			// ignore
		} catch (Throwable t) {
			slog.error("araqne log api: logger [" + getFullName() + "] cannot load wtmp file [" + path + "]", t);
		} finally {
			if (raf != null) {
				try {
					raf.close();
				} catch (IOException e) {
				}
			}
			inform.setPosition(pos);
			lastPositions.put(path, inform);
			setStates(LastPositionHelper.serialize(lastPositions));
		}
	}

	protected File getLastLogFile() {
		return new File(dataDir, "wtmp-" + getName() + ".lastlog");
	}
}